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一、选择题1.从距地面高h处水平抛出一个小石子,空气阻气不计,下列说法正确的是A.石子运动速度与时间成正比B.抛出时速度越大,在空中飞行时间越长C.抛出点高度越大,在空中飞行时间越长D.石子在空中任何时刻的速度与其竖直分速度之矢量差为一恒量2.用细绳系一小球,使它在竖直平
I. Multiple-choice questions 1. A small stone is thrown horizontally from the ground at a height h. Air does not block gas. The following statement is correct: A. The speed of the stone is proportional to time. B. The greater the speed of throwing, the more you fly in the air. The longer the time C. The greater the height of the throw point, the longer the flight time in the air. D. The stone’s vector velocity at any moment in the sky and its vertical sub-velocity is a constant. 2. Use a string to make a small ball. In the vertical plane